Transfer chutes are commonly employed in conveyor systems to transfer conveyed material from one conveyor to another. More specifically, the chutes typically receive material at an output end of one conveyor belt and direct the material to flow through the chute system to the input end of another conveyor belt which is typically at a lower elevation relative to the conveyor belt output end. Since the conveyed material can be hard and abrasive such as coal, rocks and aggregate, the chutes can be subjected to high impact and frictional forces as this material travels therethrough.
Walls of chute components are typically constructed with a less wear resistant outer shell that is lined with a harder material to provide the impact and abrasion resistance needed during transport of the conveyed material. Often the shell and liner are of different metallic materials that are secured together. For example, one known liner plate construction has a chromium carbide bimetallic plate that is welded to a soft steel backing plate. Alternatively, a tungsten carbide plate can be brazed to a soft steel backing plate to form the liner plate. In another known liner construction, hard tiles such as of ceramic material are attached to the backing plate. Once formed, the liner plates can then be bolted to the outer shell, which can be of mild steel or similar material depending on environmental needs, to form wall assemblies for the chute components.
One problem this wall assembly construction presents is that it is very difficult to know how much wear the harder liner material has undergone since the thickness of the material of the liner cannot be determined by a simple visual inspection of its interior flow surface. An additional problem relates to the practicality in performing visual inspections in the first place since it can be difficult to gain access to the interior of the chute components since they are connected together to form one, long column having walls extending entirely around and along the flow path for the conveyed material. Thus, even where ceramic tile are adhered directly to the outer shell, wear inspection of individual tiles may not be possible or may be very difficult since the interior of the chute component must be accessed for this purpose. In certain instances, such access is not available while in others it is simply impractical given the location of the chute component in the system or the location of the chute itself such as if the component is at a highly elevated position. Further, while the plates forming the components of the chute system are typically bolted together, removing these plates for liner inspection is not practical since they are usually very heavy, weighing between approximately 300 to 500 lbs each, thus requiring heavy equipment plus an operating crew for their removal. And where these components are located in difficult to access positions along the chute transfer system, the use of such heavy equipment is made all the more difficult.
Another related problem is that the liner material will wear differently depending on its location in the chute transfer system. For example, conveyor transfer chutes are typically formed from three types of components: an intake hood, intermediate components, and discharge spoons. Typically, the intake hood and the discharge spoon will have a curve or be angled to redirect conveyed material from one conveyor belt onto another, although the intermediate components can also have curves or bends to redirect the material flow as well. At these directional changes of material flow, there can be greater wear due to higher impact forces generated by the flowing material with the interior chute liner flow surface. Thus, even if the difficult process of plate removal for inspection were to be undertaken, the inspection of the plates for wear may not provide the needed wear information. This is because, in addition to being heavy, the plates can be fairly large with a 2 foot by 4 foot liner plate being considered relatively small, and with larger liner plates typically being 4 feet by 6 feet in size. As is apparent, because of the large size of the liner plates, the wear at different places along the interior flow surface of the plates can be different than at the edges where the thickness of the lining can be visually inspected.
In any case, because it is difficult to know when the liner will wear through, there is increased risk in developing a hole in the chute itself. For instance, while the harder liner material may last for six months to a year before it wears through, the softer shell material can wear through in a matter of weeks once it is exposed to the forces generated by the material flowing therealong. Thus, unless short interval wear checks are regularly performed, such as on a weekly basis, components of the transfer chutes can be irreversibly damaged which requires that the entire system be shut down so that the affected sections of the transfer chute system can be disassembled and the damaged component or components replaced.
Accordingly, there is a need for a wear inspection mechanism for conveyor transfer chutes. More particularly, there is a need for a system and method that provides ease in determining the wear of components of transfer chute systems at various locations along the material flow path.